B.l.t. bolt carrier

ABSTRACT

A bolt assembly is provided for a firearm. The bolt assembly comprises a block adapted to connect to a firearm frame and a bolt carrier adapted to reciprocate within the frame. The bolt assembly comprises a support element between the block and the bolt carrier. The support element is adapted to reciprocate within the frame with respect to the cap and with respect to the bolt carrier. The first and second spaced apart parallel rods are connected to the cap and extending from the cap. The bolt carrier defines a pair of spaced apart bores receiving the rods. A first spring is interposed between the block and the support element, a second spring is received on the first rod, and a third spring is received on the second rod.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional Patent Application No. 62/400,826 filed on Sep. 28, 2016, entitled “BLT Bolt Carrier” which is hereby incorporated by reference in its entirety for all that is taught and disclosed therein.

BACKGROUND OF THE INVENTION

Normal AR15 rifles have an extension tube that extends to the rear of the upper receiver and contains the recoil spring. Given the length of the bolt carrier, the recoil spring needs this length to compress and provide an adequate range of motion of the bolt carrier. A disadvantage of a standard AR recoil assembly, the travel of the buffer to the rear of the buffer tube causes the weapon to have more felt recoil due to more mass at the rear of the weapon. While fine for rifles with normal shoulder stocks, the protruding extension tube is a problem for pistol variants of the AR 15, as well as folding or fully collapsing stocks, which are incompatible with a fixed extension tube.

Accordingly, it is desirable to create a shorter bolt carrier that has a recoil spring capability that operates fully within the limited length of an AR-15 upper, with no extension tube. Due to spring resonance of a shorter operating platform, the BCG weight is operating closer to center axis, and less recoil is noticed as muzzle flip is reduced.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows the B.L.T. Bolt Carrier. The assembly includes a bolt carrier 1 that has opposed linear bores. A top-hat shaped center support 4 has parallel protruding guide rods 2 that extend into the bores so that the center support telescopes with respect to the bolt carrier. The two bores associated with the rods are large enough to receive compression coil springs 16 that bias the center support away from the bolt carrier.

An end cap 5 is threaded 11 to connect to the lower receiver (not shown) on existing threads where a stock might normally be attached, in line with the center of the barrel bore and bolt carrier. The cap essentially becomes the rear wall of the receiver, and the fixed frame of reference that the bolt reciprocates with respect to. A rear spring (coil, compression) 17 is captured between the center support 4 and the cap. Thus, as the bolt reciprocates, the main springs 16 and rear spring 17 both compress, each storing some of the recoil energy for recover for stripping and chambering the next round. The center support 4 floats between the bolt carrier and the cap during recoil cycling, at a middle position between the two.

If a single rear spring were used (as in a conventional AR-15), it would have to be much longer, and the “end cap” would need to be lengthened to become an extension tube. This is partly due to the need to absorb recoil energy, and partly due to the length of the fully collapsed spring when the coils are stacked against each other, a condition normally to be avoided. It is not possible to extend the rear spring forward into or around the bolt carrier because of the needed structure and functions of the bolt carrier. However, the main spring that resides in part within the bolt carrier bore provides this added spring capability without lengthening the rear spring undesirably. The three springs are essentially end to end, and the entire rear spring remains to the rear of the entire front spring in all conditions. These are serially connected with the center support gripped or pinched between them, and each spring has a size and shape based on the space it has to work within the B.L.T. BCG.

In this exploded view, the image shows the rear view of the main spring zero footprint pocket (6), the guide rods (2) that are attached to the center support (4). The end cap is the end of the B.L.T. BCG that houses the solid height of the rear spring.

FIG. 2 shows the installed length with a frontal view looking to the right side to the rear. The B.L.T. utilizes a milspec bolt. The bore is milspec diameter (15).

FIG. 3 shows the installed length with the right side of the B.L.T. BCG. The guide rod bore hole goes through the entire BCG. The end cap shows the threads with a 1 3/16″-16 tpi pitch is how the end cap attaches to the lower receiver.

FIG. 4 shows the view when the B.L.T. carrier is in collapsed position from being fired. In this position, the retention guide rod is showing through the ejection port cutout. The center support recesses internally into the end cap fully compressed.

FIG. 5 shows a top view image looking down on the installed length, ready to fire. This spring technology has zero footprint solid height. The main springs recess internally in the carrier. The rear spring recesses into the end cap.

The rear spring 17 presses on the rear surface of the flange of the center support 4, and the main springs press on the front surface of the flange, guided by the rods.

FIG. 6 shows the B.L.T. Bolt Carrier. The assembly includes a bolt carrier 1 that has opposed linear bores. A top-hat shaped center support 4 has parallel protruding guide rods 2, 3 that extend into the bores so that the center support telescopes with respect to the bolt carrier. The retention guide rod 3 has a flared tip that prevents the center support assembly from falling out of the bolt carrier. The bore associated with rod 2 is large enough to receive a compression coil spring 16 (not shown) that biases the center support away from the bolt carrier.

An end cap 5 is threaded 11 to connect to the lower receiver (not shown) on existing threads where a stock might normally be attached, in line with the center of the barrel bore and bolt carrier. The cap essentially becomes the rear wall of the receiver, and the fixed frame of reference that the bolt reciprocates with respect to. A rear spring (coil, compression) 17 is captured between the center support 4 and the cap. Thus, as the bolt reciprocates, the main spring 16 and rear spring 17 both compress, each storing some of the recoil energy for recovery for stripping and chambering the next round. The center support 4 floats between the bolt carrier and the cap during recoil cycling, at a middle position between the two.

If a single rear spring were used (as in a conventional AR-15) it would have to be much longer, and the “end cap” would need to be lengthened to become an extension tube. This is partly due to the need to absorb recoil energy, and partly due to the length of the fully collapsed spring when the coils are stacked against each other, a condition normally to be avoided. It is not possible to extend the rear spring forward into or around the bolt carrier because of the needed structure and functions of the bolt carrier. However, the main spring that resides in part within the bolt carrier bore provides this added spring capability without lengthening the rear spring undesirably. The two springs are essentially end to end, and entire rear spring remains to the rear of the entire front spring in all conditions. These are serially connected with the center support gripped or pinched between them, and each spring has a size and shape based on the space it has to work within.

In this extended position/installed length is a see through image that shows internal view of the main spring zero footprint pocket (6), the smooth guide rod (2) that is attached to the center support (4) by the threaded end (8), the retention guide rod (3) and the flared tip (7) that is inserted through the carrier from the front to the center support where it is threaded into the center support (4), now the carrier (1), main spring (16), guide rods and center support connected in operational order. The end cap is the end of the B.L.T. BCG that houses the solid height of the rear spring.

FIG. 7 shows installed length showing a frontal view looking to the right side to the rear. The B.L.T. utilizes a milspec bolt. The bore is milspec diameter (15), utilizes milspec dust cover cutout (12)

FIG. 8 shows installed length showing the right side of the B.L.T. BCG, the guide rod bore hole goes through the milspec ejection port cutout. The end cap shows the threads with a 1 3/16″-16 tpi pitch is how the end cap attaches to the lower receiver

FIG. 9 shows the B.L.T. carrier is in collapsed position from being fired. In this position the retention guide rod is showing through the ejection port cutout. The center support recesses internally into the end cap.

FIG. 10 shows a cutaway view from the bottom looking up in the collapsed position when in recoil from being fired.

FIG. 11 shows a cutaway view from the top looking down in the extended install length ready to be fired.

FIG. 12 shows a top view image looking down on the installed length, ready to fire. This spring technology with zero footprint solid height. The main spring on the left side shows how the spring recesses internally in the carrier. The rear spring recesses into the end cap.

The rear spring 17 presses on the rear surface of the flange of the center support 4, and the main spring presses on the front surface of the flange, guided by the rod 2.

FIG. 13 shows the same view as FIG. 12, but in the fully compressed condition in full recoil. The center support 4 ensures that if a first one of the springs is fully compressed so that the coils touch each other, then the other spring will have some accommodation to limit this “crash” before it can have a harmful effect.

FIG. 14 is fully compressed no springs.

FIG. 15 is a frontal view looking from the left side to the rear.

List of the parts:

1. B.L.T. (bufferless technology) Bolt Carrier

2. Guide Rod Smooth

3. Guide Rod Retention

4. Center support

5. End cap

6. Main spring “zero footprint” pocket

7. Flared end of retention guide rod

8. Threaded guide rod ends

9. Standard Cam cutout

10. Standard gas key cutout

11. End cap threads (standard buffer threads)

12. Standard dust cover cutout

13. Standard Gas stake bolt holes

14. Gas hole

15. Milspec B.C.G. bore hole

16. Main spring

17. Rear spring 

The claimed invention is:
 1. A bolt assembly for a firearm comprising: a block adapted to connect to a firearm frame; a bolt carrier adapted to reciprocate within the frame; a support element between the block and the bolt carrier; the support element adapted to reciprocate within the frame with respect to the cap and with respect to the bolt carrier; first and second spaced apart parallel rods connected to the cap and extending from the cap; the bolt carrier defining a pair of spaced apart bores receiving the rods; a first spring interposed between the block and the support element; a second spring received on the first rod; and a third spring received on the second rod. 